This invention relates to printing presses, and more particularly, to an apparatus, such as a spray dampener, for dispensing fluid to a roller of a printing press.
In the printing art, and especially the modern newspaper printing art, various devices and systems have been disclosed for applying a fluid to the rollers of printing presses, to accomplish dampening, cleaning, the prevention of offset and the like. The art as presently practiced includes such time-honored devices as open, fluid filled troughs for bathing rollers and such modern devices as spray dampeners which dampen rollers by fluid mist sprayed from nozzles positioned alongside the rollers at spaced mounting positions along frame members called spray bars.
Spraying devices offer many advantages over troughs, such as easier maintenance and greater consistency in fluid application. All such spraying devices presently known have some common features. First, the devices use air as a medium for the spraying of the desired fluids, to atomize the fluids and thereby provide a desirably even and light spray. Second, all such devices control and vary spray quantity by regulating fluid pressure and/or the configurations of the nozzle openings or orifices. Spray quantity is varied to provide an application of fluid to the roller which increases or decreases in quantity relative to press operation factors, such as press speed. An example of a spray dampening device is found in U.S. Pat. No. 4,064,801.
While the mentioned fluid application devices have proven somewhat desirable, they have consistently yielded to several long-standing problems. As a first example, they have experienced frequent failures, and high maintenance demands due to nozzle clogging. This problem has generally been caused by the air/fluid spray nozzles plugging due to ink mist, paper dust and water deposits. The plugging deforms or eliminates spray patterns, starving roller areas of needed fluid. As a second example, they have experienced frequent failures and high maintenance requirements due to inconsistences in their metering devices. Metering pumps have frequently malfunctioned from debris and leaking seals. Metering orifices have become uncalibrated from vibration. As a third example, they have required cumbersome controls, which occupy valuable operator space on the presses.